On Wednesday forensic investigators were seen working inside Letby’s house about 1.5km from the hospital. A blue tent remains on the driveway, while the neighbouring properties either side are still taped off. Two police community support officers were guarding the entrance to the property where Letby is thought to have lived for at least two years.

A neighbouring couple, who did not wish to be named, said they recognised Letby’s face in the newspaper and had seen her on their street. “We only knew her to say hello to, nothing more,” one said.

Steve Doyle, from Ellesmere Port, said he had seen Letby in the Countess of Chester’s unit for women and children when his daughter was admitted to hospital. “I remember distinctly her face and she was part of that unit, on ward 30,” he said. “We didn’t get to talk to her but I recognised her face.”

Letby, a University of Chester graduate, is understood to have worked at the hospital as a paediatric nurse since 2011, when she graduated, and before that as a student nurse during her three years of training.

She was pictured smiling and holding up a baby gown in the hospital’s internal newsletter, the Standard, in March 2013 in which she spoke about her role in the neonatal unit.

She said: “My role involves caring for a wide range of babies requiring various levels of support. Some are here for a few days, others for many months, and I enjoy seeing them progress and supporting their families.

“I am currently undergoing extra training to develop and enhance my knowledge and skills within the intensive care area and have recently completed a placement at Liverpool women’s hospital.”

She added that plans for the hospital to expand of its neonatal unit would “provide a greater degree of privacy and space for parents and siblings”.

In a second appearance in the hospital newsletter in August 2015, Letby was pictured smiling for a story about how nurses had raised £1.5 million (US$2 million) and reached the halfway mark in a £3 million effort to build a new “state of the art” baby unit.

A photograph of Letby in her graduation robes and gown appeared in her local Hereford Times newspaper in December 2011, along with a note from her parents: “We are so proud of you after all your hard work. Love Mum and Dad.”

Plain-clothes police officers were seen searching the house of her parents, Susan, 58, and John, 73, in Herefordshire after her arrest on Tuesday.

A neighbour, who did not want to be named, said: “Lucy is so dedicated to her job. I can’t imagine that at all. Lucy just spent a week in Torquay on holiday with her parents.

“I just truly can’t believe it. I lived here since she was born, she was a good little girl. She was a delight. She’s is an only child and I believe she got her job as a nurse from her studies at Chester University. Her parents must be going through hell.

“I’m really close to them – I mean, we housesit for each other when one of us goes away. I knocked earlier but got no response and it makes me upset knowing that I can’t help them.”

Another neighbour who wanted to remain anonymous said: “Lucy was just a quiet girl. Nothing strange about her – she was just a normal, lovely girl. The family must be in bits over this.

“It’s just really shocking. She was just here on Saturday, we saw her with her father and she seemed normal. I think her father was driving her back home because they had just got back from a holiday.

“We’ve known Lucy since she was about three years old and she was lovely, she always has been. But this is just really shocking.”

Police launched an investigation in May last year into the deaths of 15 babies and six non-fatal collapses at the women and children’s unit of the Countess of Chester hospital between June 2015 and June 2016. The force said on Tuesday the inquiry had widened to cover the deaths of 17 babies and 15 non-fatal collapses between March 2015 and July 2016.